WASHINGTON — At what point do breakdowns in discipline put the country’s nuclear security in jeopardy?

And when does a string of embarrassing episodes in arguably the military’s most sensitive mission become a pattern of failure?

Defense Secretary Chuck Hagel is now concerned “there could be something larger afoot here,” according to his chief spokesman, and “wants this taken very, very seriously.”

The disclosures of disturbing behavior by nuclear missile officers are mounting and now include alleged drug use and exam cheating. Yet Air Force leaders insist the trouble is episodic, correctable and not cause for public worry.

The military has a well-established set of inspections and other means of ensuring the safety of its nuclear weapons. But as in any human endeavor, military or civilian, the key to success is the people, not the hardware.

Until recently, Hagel said little in public about the setbacks and missteps in the nuclear missile force reported by The Associated Press beginning in May.

Last week, Hagel made the first visit to a nuclear missile launch control center by a Pentagon chief since 1982. He praised the force’s professionalism, even though minutes before, officials informed him that a few missile launch officers at another base were suspected of illegal drug use.

Air Force Secretary Deborah Lee James, just four weeks into her tenure as the service’s top civilian official, told reporters Wednesday the Air Force’s chief investigative arm is investigating 11 officers at six bases who are suspected of illegal drug possession.

She said that probe led to a separate investigation of dozens of nuclear missile launch officers for cheating on routine tests of their knowledge of the tightly controlled procedures required to launch missiles under their control.

At least 34 launch officers, all at Malmstrom Air Force Base, Mont., had their security clearances suspended and are not allowed to perform launch duties pending the outcome of the investigation.

They stand accused of cheating, or tolerating cheating by others, on a routine test of their knowledge of how to execute “emergency war orders.” Those are the highly classified procedures the officers would use, upon orders from the president, to launch their nuclear-tipped missiles.

The alleged cheaters are said to have transmitted test answers by text message to colleagues. That is a violation not only of their own personal integrity but also of security classification rules.

The commander at Malmstrom, Col. Robert W. Stanley II, said in a telephone interview Friday it’s not “off base” to think the cheating points to a deeper problem in the intercontinental ballistic missile force.

“But I do think it’s far more than just us. I think this is a sort of cultural thing our society is going through” in which too many people are accustomed to “putting blinders on and just walking past problems.”

This is reflected in the cheating scandal, he said, where 17 of the 34 did not cheat but knew about the cheating and failed to report it.

“In ICBMs we can’t tolerate that,” Stanley said.

In response to the cheating, the Air Force retested every available ICBM launch control officer at Malmstrom as well as the two other bases operating Minuteman 3 missiles: F.E. Warren Air Force Base, Wyo., and Minot Air Force Base, N.D.

The Air Force said Friday of 472 officers who retook the “T-1” test, 21 failed and will receive new training before they can return to duty. Twenty-seven were not available to be tested this past week, according to a Pentagon spokesman, Col. Steve Warren.

Thus a total of 82 launch officers, including the 34 who were suspended, are not available to perform launch control duties, and Warren said that is “having an impact” on the ICBM force. He added, however, it has not interrupted the 24/7 combat readiness of all Minuteman 3 missiles or made them less secure.

James said she was confident the Minuteman 3 arsenal is being safely and reliably operated and controlled, but said she was “profoundly disappointed” in those involved in the drug and cheating investigations.

“This was a failure of some of our airmen,” she said. “It was not a failure of the nuclear mission.”

James said she is reassured by “checks and balances” in the system, including periodic inspections at the ICBM bases. She said she would travel to each of the three ICBM bases this week to see for herself.

“In any given organization there are issues,” she said when asked at a Pentagon news conference about the implications of the latest investigations.